Publications (44)106.31 Total impact
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Article: Microwave-assisted three-component domino reaction: Synthesis of indolodiazepinotriazoles
Beilstein J. Org. Chem. 01/2013; 9:401. -
Article: Microwave-assisted three-component domino reaction: Synthesis of indolodiazepinotriazoles.
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ABSTRACT: A microwave-assisted three-component protocol involving N-1 alkylation of 2-alkynylindoles with epichlorohydrin, ring opening of the epoxide with sodium azide, and an intramolecular Huisgen azide-internal alkyne 1,3-dipolar cycloaddition domino sequence has been described. The efficacy of the methodology has been demonstrated by treating various 2-alkynylindoles (aromatic/aliphatic) with epichlorohydrin and sodium azide furnishing annulated tetracyclic indolodiazepinotriazoles in satisfactory yields.Beilstein Journal of Organic Chemistry 01/2013; 9:401-5. · 2.52 Impact Factor -
Article: Cascade intermolecular Michael addition-intramolecular azide/internal alkyne 1,3-dipolar cycloaddition reaction in one pot.
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ABSTRACT: A rapid one-pot protocol for the synthesis of indole-based polyheterocycles via a sequential Lewis acid catalyzed intermolecular Michael addition and an intramolecular azide/internal alkyne 1,3-dipolar cycloaddition reaction has been described. The generality of the method has been demonstrated by treating a series of aromatic/aliphatic 2-alkynyl indoles with substituted (E)-1-azido-2-(2-nitrovinyl)benzenes to furnish annulated tetracyclic indolo[2,3-c][1,2,3]triazolo[1,5-a][1]benzazepines in good yields.Organic Letters 03/2012; 14(7):1804-7. · 5.86 Impact Factor -
Article: Engineering of indole-based tethered biheterocyclic alkaloid meridianin into β-carboline-derived tetracyclic polyheterocycles via amino functionalization/6-endo cationic π-cyclization.
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ABSTRACT: A mild, efficient and versatile method has been developed for the construction of a functionalized natural product, meridianin, and its post conversion to pyrimido-β-carboline by cationic π- cyclization. The strategy involves the introduction of an amino group at the C-5 of the pyrimidine ring and utilizing the nucleophilictiy of the C-2 in the indole ring to facilitate cationic π-cyclization.Beilstein Journal of Organic Chemistry 01/2012; 8:1901-8. · 2.52 Impact Factor -
Article: Three-component tandem reaction involving acid chlorides, terminal alkynes, and 2-aminoindole hydrochlorides: synthesis of α-carboline derivatives in aqueous conditions via regioselective [3 + 3] cyclocondensation.
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ABSTRACT: An efficient synthesis toward highly diversified α-carboline derivatives via a three-component tandem reaction using acid chlorides, terminal alkynes, and 2-aminoindole hydrochlorides has been described. The salient feature of the one-pot strategy involves regioselective [3 + 3]-cyclocondensation and the presence of water in the reaction medium to facilitate cyclization. Nonaqueous conditions furnished products in poor yields.The Journal of Organic Chemistry 11/2011; 76(24):10154-62. · 4.45 Impact Factor -
Article: One-pot Zn/CuI/TFA-catalyzed domino three-component-carbocyclization reaction involving biphenyl-2-carbaldehydes/alkynes/piperidine: allenes-mediated construction of phenanthrenes.
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ABSTRACT: A one-pot protocol involving Zn/CuI/TFA-catalyzed domino three-component and subsequent carbocyclization reactions is described. The reaction proceeds via formation of propargyl amines from biphenyl-2-carbaldehydes/terminal alkynes/piperidine followed by the elimination of piperidine and ring closure to furnish phenanthrene derivatives in good yields. The strategy involves C(sp)-H activation-CH functionalization with imine-alkyne activation-1,5 hydride shift-β-elimination of piperidine-allene formation-6π cycloaddition-isomerization domino sequence. Evidence for the involvement of allenes as an intermediate during carbocyclization is discussed.The Journal of Organic Chemistry 11/2011; 76(24):10122-8. · 4.45 Impact Factor -
Article: Synthesis of iodo-indoloazepinones in an iodine-mediated three-component domino reaction via a regioselective 7-endo-dig iodo-cyclization pathway.
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ABSTRACT: An efficient and rapid synthetic strategy for the naturally occurring indoloazepinone scaffold via a three-component reaction of indole-2-carboxamides, 1,3-disubstituted propargyl alcohols, and I(2) is described. The strategy involves a C-H functionalization-alkyne activation-intramolecular hydroamidation-deprotonation domino sequence. The salient feature of this sequence is regioselective electrophilic 7-endo-dig iodo-cyclization during the intramolecular hydroamidation to afford a seven-membered azepinone ring annulated to the indole.The Journal of Organic Chemistry 08/2011; 76(16):6798-805. · 4.45 Impact Factor -
Article: Unprecedented Cu-catalyzed coupling of internal 1,3-diynes with azides: one-pot tandem cyclizations involving 1,3-dipolar cycloaddition and carbocyclization furnishing naphthotriazoles.
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ABSTRACT: A one-pot protocol for the synthesis of triazole-annulated polyheterocycles via metal-catalyzed coupling of internal 1,4-disubstituted 1,3-diynes and organic azides has been described. The mechanistic rationale for the reaction suggests tandem cyclizations involving copper-catalyzed cycloaddition and 6-endo carbocyclization reactions. The cascade cyclization leads to an increase in molecular complexity to furnish naphtho[1,2-d]triazoles in satisfactory yields. The generality of the method has been demonstrated by using a series of aromatic/aliphatic azides and symmetrical internal 1,3-diynes.Organic Letters 06/2011; 13(12):3162-5. · 5.86 Impact Factor -
Article: Three component tandem reactions involving protected 2-amino indoles, disubstituted propargyl alcohols, and I2/ICl: iodo-reactant controlled synthesis of dihydro-α-carbolines and α-carbolines via iodo-cyclization/iodo-cycloelimination,
Tetrahedron Letters 01/2011; 52:65. · 2.68 Impact Factor -
Article: Hydro-amination/-amidation of 1,3-diynes with indoles/azoles/amides under modified Ullmann conditions: Stereo- and regio-selective synthesis of Nalkenynes via N-H bond activation
Tetrahedron Letters 01/2011; · 2.68 Impact Factor -
Article: Pictet-Spengler reaction revisited: Engineering of tetherd biheterocycles into annulated polyheterocycles
Curr. Org. Synthesis. 01/2011; -
Article: Three-component tandem reaction involving acid chlorides, terminal alkynes, and ethyl 2-amino-1H-indole-3-carboxylates: synthesis of highly diversified pyrimido[1,2-a]indoles via sequential Sonogashira and [3+3] cyclocondensation reactions
Tetrahedron Letter. 01/2011; 52:4288. -
Article: Three-component tandem reaction involving acid chlorides, terminal alkynes, and ethyl 2-amino-1H-indole-3-carboxylates: synthesis of highly diversified pyrimido[1,2-a]indoles via sequential Sonogashira and [3+3] cyclocondensation reactions
Tetrahedron Lett. 01/2011; 52:4288. -
Article: Three component tandem reactions involving protected 2-amino indoles, disubstituted propargyl alcohols, and I2/ICl: iodo-reactant controlled synthesis of dihydro-α-carbolines and α-carbolines via iodo-cyclization/iodo-cycloelimination
Tetrahedron Lett. 01/2011; 52:65. -
Article: Efficient Synthesis of Naturally Occurring Skeleton 5–7–6 Tricyclic Pyrrolo[2,1-c][1,4]benzodiazepin-5-one and Its Derivatives via Cationic π-Cyclization
Synthesis. 01/2010; -
Article: Water-Accelerated Cationic π-(7-endo) Cyclisation: Application to Indole-Based Peri-Annulated Polyheterocycles
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ABSTRACT: An efficient and versatile method for the synthesis of indolebased polycyclic indolo-benzazepine and its derivatives through water-accelerated cationic π-cyclisation is described.The strategy involves condensation of arylamine moieties linked to C-4 in indole/azaindole systems with arylaldehydes in water containing catalytic amount of Bronsted acids. The C–C bond formation in water is complete within 10–30 min,furnishing the title compounds in excellent yields and purities,whereas in organic solvents 10–12 h are required.Furthermore, aldehydes both with electron-donating andwithdrawing substituents facilitate the π-cyclisation equally.Eur. J. Org. Chem. 01/2010; -
Article: Water Accelerated Cationic π-(7-endo) Cyclisation: Application to Indole-Based Peri-Annulated Polyheterocycles
Eur. J. Org. Chem. 01/2010; -
Article: Three-component reaction involving metal-free heteroannulation of N-Boc-3-amido indole, aryl aldehydes, and aromatic alkynes under microwave conditions: synthesis of highly diversified δ-carbolines
Tetrahedron Lett. 01/2010; 51:6022. -
Article: Water-Accelerated Cationic π-(7-endo) Cyclisation: Application to Indole-Based Peri-Annulated Polyheterocycles
European Journal of Organic Chemistry 01/2010; · 3.33 Impact Factor -
Article: Catalyst/ligand-free synthesis of benzimidazoles and quinazolinones from amidines via intramolecular transamination reaction
Tetrahedron Letters 01/2010; 51:1887. · 2.68 Impact Factor
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Institutions
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2003–2013
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Central Drug Research Institute
- Medicinal and Process Chemistry Division (CDRI)
Lucknow, Uttar Pradesh, India
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